We made constant pressure filtration (Fig.1) of the excess activated sludge using the microfiltration hollow fiber made of polyethylene with pore size 0.1 μm with/without aeration condition under various suction pressure(8.0 or 61.3 kPa).

We used three samples as described below. (1) "Activated sludge (AS)", which is the excess activated sludge from the municipal wastewater treatment plant in Matsuyama, Japan, settled for 18 h in the refrigerator (5 ^oC). (2) "Centrifugal settling supernatant (CSS)", which is the supernatant of "Activated sludge" by the centrifugal settling (3000 rpm, 1600 g, 10 min). (3) "Glass fiber filtrate (GFF)", which is the filtrate of "Centrifugal settling supernatant" with glass fiber filter (nominal pore size: 0.6 μm).

Thereby, we could widely examine the effect of various kinds of solids in the activated sludge on the filtration characteristics of this hollow fiber microfiltration...

...The influence of the aeration operation on the constant pressure filtration characteristics of activated sludge can be quantitatively shown....